Characterization of an organelle integrity checkpoint

细胞“检查点”在其他不相关的细胞事件之间创建层次结构。例如，由于“DNA复制检查点”的存在，DNA复制的延迟会导致核分裂的延迟。它们是连接这些不相关事件的信号转导途径，例如，感知DNA复制中的阻滞是通过信号传导途径来抑制核分裂的。大多数检查点已经在细胞周期中被确定。然而，存在额外的检查点，例如响应细胞骨架扰动的形态发生检查点。基于我以前的工作，我提出存在一个检查点，将真核细胞器的完整性，内质网，与分化程序联系起来，这将需要一个完整的内质网。这个检查点的目的是，只有能够成功完成分化过程的细胞才会启动分化过程。内质网功能受损的细胞会在完成分化程序的过程中死亡。检查点由两个信号事件组成，我已经对其中一个进行了详细描述。第二个问题目前还没有得到很好的理解。我们目前所知道的唯一一件事是，缺乏检查点上游元素的细胞在启动分化程序时存在缺陷。此外，参与该检查点的第一个信号活动的基因不参与第二个信号活动。从分子的角度来看，这让我有机会通过研究这第二个信号转导事件来发现一个新的信号转导途径。我将在贝克酵母中进行一系列遗传实验，以确定内质网完整性检查点的第二信号通路的组成部分。然后进行生化实验以进一步了解这些基因和蛋白质在这一信号通路中的作用。

Cellular 'checkpoints' create a hierarchy between otherwise unrelated cellular events. For example, a delay in DNA replication results in a delay in nuclear division due to the 'DNA replication checkpoints'. They are signal transduction pathways that link these unrelated events, e.g. sensing of a block in DNA replication is transduced by a signalling pathway to inhibit nuclear division. The majority of checkpoints have been identified in the cell cycle. However, additional checkpoints exist, e.g. the morphogenesis checkpoint that responds to perturbations in the cytoskeleton. Based on my previous work I propose that a checkpoint exists that links integrity of an eukaryotic organelle, the endoplasmic reticulum, to differentiation programs that down the line will require an intact endoplasmic reticulum. The purpose of this checkpoint is that only cells that can successfully complete the differentiation process will initiate it. Cells with compromised ER function would die trying to complete the differentiation program. The checkpoint consists of two signalling events, one of which I already characterized in some detail. The second one is less well understand at the moment. The only thing we currently know is that cells lacking upstream elements of the checkpoint are defective in initiating the differentiation program. Further, genes involved in the first signalling activity of this checkpoint are not involved in the second signalling event. From a molecular perspective this gives me the opportunity to uncover a novel signal transduction pathway by studying this second signalling event. I will use a range of genetic experiments in Baker's yeast to identify components of this second signalling pathway of this endoplasmic reticulum integrity checkpoint. Biochemical experiments will then be performed to further understand the role of these genes and proteins in this signalling pathway.